Confused with psfgen module of VMD

I am fairly new to VMD and programming in general.I need to combine two pdb files of subunits into a combined pdb and psf file with both subunits.I used the Namd tutorial and used two pdb files named BChain270VerCTrue.pdb and barn_noH2o_ChainD.pdb and ran this pgn in VMD:

package require psfgen topology top_all27_prot_lipid.inp pdbalias residue HIS HSE pdbalias atom ILE CD1 CD segment A {pdb BChain270VerCTrue.pdb} segment D {pdb barn_noH2o_ChainD.pdb} coordpdb BChain270VerCTrue.pdb A coordpdb barn_noH2o_ChainD.pdb D guesscoord writepdb BarnaseBarnstar270True.pdb writepsf BarnaseBarnstar270True.psf

However, this creates a sort of mangled pdb that has both subunits covalently bonded. How could I fix this?

This is how the two pdb files look when just used separately in VMD:

This is what the code spits out: